Method and apparatus of error handling for video coding using intra block copy mode

Abstract

In order to overcome the issue caused by a decoded block vector (BV) pointing to a reference block overlapping with an unavailable area, various methods are disclosed. According to one method, if the reference block overlaps with an unavailable area, the reference pixels in the unavailable area are generated for IntraBC prediction of the current block by padding from neighboring available pixels. The padding can be done in the horizontal direction and then the vertical direction. The padding may also done in the vertical direction first and then horizontal direction. In another method, if the reference block overlaps with an unavailable area, the reference pixels in the unavailable area are generated for IntraBC prediction of the current block by using previous decoded pixels in the unavailable area. A pre-defined value may also be used for the unavailable area.

The invention claimed is: 
     
       1. A method of error handling for a video decoding system using an Intra Block Copy (IntraBC) mode, comprising:
 determining a decoded BV (block vector) for a current block in a current picture; 
 determining a reference block in the current picture, wherein the reference block is pointed by the decoded BV from the current block; 
 if the reference block overlaps with an unavailable area, generating reference pixels in the unavailable area for IntraBC prediction of the current block by padding from neighbouring available pixels, by using previous decoded pixels in the unavailable area, or by using a pre-defined value; 
 setting all pixels in a storage area of the current picture to the pre-defined value before decoding the current picture; and 
 decoding the current block in the IntraBC mode using the reference block. 
 
     
     
       2. The method of  claim 1 , wherein said padding from neighbouring available pixels corresponds to horizontal padding followed by vertical padding. 
     
     
       3. The method of  claim 1 , wherein said padding from neighbouring available pixels corresponds to vertical padding followed by horizontal padding. 
     
     
       4. The method of  claim 1 , further comprising storing a previous decoded block in the storage area of the current picture, wherein the reference block for the current block is fetched directly from the storage area of the current picture regardless whether the reference block is in the unavailable area or not. 
     
     
       5. The method of  claim 4 , wherein the pre-defined value is equal to (1<<(bit_depth−1)), and wherein bit_depth corresponds to bit depth of the current picture. 
     
     
       6. The method of  claim 5 , wherein the pre-defined value is signalled in a SPS (sequence parameter set), PPS (picture parameter set), or slice header. 
     
     
       7. The method of  claim 1 , wherein the pre-defined value is equal to (1<<(bit_depth−1)), and wherein bit_depth corresponds to bit depth of the current picture. 
     
     
       8. The method of  claim 1 , wherein all pixels in the reference block are generated using the pre-defined value. 
     
     
       9. The method of  claim 1 , wherein the pre-defined value is signalled in a SPS (sequence parameter set), PPS (picture parameter set), or slice header. 
     
     
       10. A video decoding system, comprising:
 one or more processors configured to execute program code to:
 determine a decoded BV (block vector) for a current block in a current picture; 
 determine a reference block in the current picture, wherein the reference block is pointed by the decoded BV from the current block; 
 if the reference block overlaps with an unavailable area, generate reference pixels in the unavailable area for IntraBC prediction of the current block by padding from neighbouring available pixels, by using previous decoded pixels in the unavailable area, or by using a pre-defined value; 
 set all pixels in a storage area of the current picture to the pre-defined value before decoding the current picture; and 
 decode the current block in the IntraBC mode using the reference block. 
 
 
     
     
       11. A non-transitory, machine-readable storage media comprising machine-readable code that, when executed by one or more processors, causes the one or more processors to:
 determine a decoded BV (block vector) for a current block in a current picture; 
 determine a reference block in the current picture, wherein the reference block is pointed by the decoded BV from the current block; 
 if the reference block overlaps with an unavailable area, generate reference pixels in the unavailable area for IntraBC prediction of the current block by padding from neighbouring available pixels, by using previous decoded pixels in the unavailable area, or by using a pre-defined value; 
 set all pixels in a storage area of the current picture to the pre-defined value before decoding the current picture; and 
 decode the current block in the IntraBC mode using the reference block.